Power
You'll have a great deal of power and expertise over part of the human anatomy. You're able to sit there and say with certainty and authority: "That man has kidney stones! We must act!"
And you'll have your minions go to work for you. Because you'll be a specialist, you'll have a lot of power in terms of (usually) being your own boss, and also being the boss of other people.
Money is power (we think—we'd need more money to tell you for certain), and you'll definitely have money. Also, the second you play the "doctor card" at any social event, you'll immediately gain the respect of the entire room. Maybe just don't get into the specifics of your specialty while people are eating.